A nativist moral psychology, modeled on the successes of theoretical linguistics, provides the best framework for explaining the acquisition of moral capacities and the diversity of moral judgment across the species. After a brief presentation of a poverty of the moral stimulus argument, this chapter sketches a view according to which a so-called Universal Moral Grammar provides a set of parameterizable principles whose specific values are set by the child's environment, resulting in the acquisition of a moral idiolect. The principles and parameters approach predicts moral diversity, but does not entail moral relativism.
Keywords: moral psychology, moral judgment, moral stimulus, universal moral grammar, moral relativism